Through which one of the following mediums is the velocity of a sound wave the greatest?
a. water
b. lead
c. air
d. steel

A-4.60 μc charge is moving at a constant speed of 6.80×105 m/s in the +x−direction relative to a reference frame. at the instant when the point charge is at the origin, what is the magnetic-field vector it produces at the following points.

Avoltaic cell converts chemical energy to

Why does lightning travel from clouds to the ground?